This invention relates generally to a document quality option for an electrophotographic printing machine, and more particularly concerns a user selectable device to produce high quality color prints.
In a typical electrophotographic printing process, a photoconductive member is charged to a substantially uniform potential so as to sensitize the surface thereof. The charged portion of the photoconductive member is exposed to selectively dissipate the charges thereon in the irradiated areas. This records an electrostatic latent image on the photoconductive member. After the electrostatic latent image is recorded on the photoconductive member, the latent image is developed by bringing a developer material into contact therewith. Generally, the developer material comprises toner particles adhering triboelectrically to carrier granules. The toner particles are attracted from the carrier granules to the latent image forming a toner powder image on the photoconductive member. The toner powder image is then transferred from the photoconductive member to a copy sheet. In the case of color electrophotography, each of the color separations must be independently developed on the photoconductor before it can be transferred, either directly to the sheet, or more commonly to an intermediate transfer belt. The toner particles are then heated to permanently affix the powder image to the copy sheet.
For purposes of reliability, it is desirable to provide a photoconductive drum or belt which is large enough to accommodate several image containing pitches or panels. It is the nature of these photoconductive materials to contain electrical properties which tend to vary as a function of position. Therefore it is to be expected that each panel on a photoconductive element will have properties that differ slightly from the adjacent panels. Because the accurate rendering of color images depends on very precise control of the electrostatic potentials throughout the image, it is to be expected that the very best quality will be obtained when the same physical panel is used to develop all of the color separations for a given image. It is desirable to enable a user to select a standard or an enhanced color quality (CQ)mode of operation. This can be done by means of a user interface. In the enhanced CQ mode, each color separation of a given image is developed on the same photoreceptor panel. This entails waiting for as many as N-1 wasted pitches for an N pitch photoreceptor, but at the same time it improves image uniformity since the effect of panel to panel variations are significantly reduced. In the standard CQ mode, each separation is developed on the subsequent panel which significantly improves productivity but adds non uniformity to the image.
The following disclosures may relate to various aspects of the present invention:
EP-A 0,665,676 PA1 Inventor: Winter, et al. PA1 Filed: Jan. 27, 1994 PA1 EP-A 0,665,677 PA1 Inventor: Winter, et al. PA1 Filed: Jan. 27, 1994 PA1 EP-A 0,665,675 PA1 Inventor: Naik, et al. PA1 Filed: Jan. 27, 1994
Some portions of the foregoing disclosures may be briefly summarized as follows:
EP-A 0,665,676 describes a printer in which different print quality modes invoke different color rendering options for a particular object to be printed in a composite document having objects of differing types in a color inkjet printer.
EP-A 0,665,677 describes a method of using a printer system for identifying one or more different types of color objects in a document, selecting a preferred rendering option such as halftoning and/or color matching for each one of such different color object types, respectively, and then printing the document in accordance with the rendering options selected for each of such different color object types, in a printing system such as an inkjet color printer.
EP-A 0,665,675 discloses in a color printer system such as a color inkjet printer, an interactive user interface allows a choice between one-button automatic control of color output or multibutton control of color output, with both automatic and manual options providing independent control for color halftoning and for color correction based on the types of objects to be printed.